336Identifying new plant microRNAs using EST analysis Identifying new plant microRNAs using EST analysis Identifying new plant microRNAs using EST analysis Identifying new plant microRNAs using EST analysis Identifying new plant microRNAs using EST analysis ABSTRACTSeventy-five previously known plant microRNAs (miRNAs) were classified into 14 families according to their gene sequence identity. A total of 18,694 plant expressed sequence tags (EST) were found in the GenBank EST databases by comparing all previously known Arabidopsis miRNAs to GenBank's plant EST databases with BLAST algorithms. After removing the EST sequences with high numbers (more than 2) of mismatched nucleotides, a total of 812 EST contigs were identified. After predicting and scoring the RNA secondary structure of the 812 EST sequences using mFold software, 338 new potential miRNAs were identified in 60 plant species. miRNAs are widespread. Some microRNAs may highly conserve in the plant kingdom, and they may have the same ancestor in very early evolution. There is no nucleotide substitution in most miRNAs among many plant species. Some of the new identified potential miRNAs may be induced and regulated by environmental biotic and abiotic stresses. Some may be preferentially expressed in specific tissues, and are regulated by developmental switching. These findings suggest that EST analysis is a good alternative strategy for identifying new miRNA candidates, their targets, and other genes. A large number of miRNAs exist in different plant species and play important roles in plant developmental switching and plant responses to environmental abiotic and biotic stresses as well as signal transduction. Environmental stresses and developmental switching may be the signals for synthesis and regulation of miRNAs in plants. A model for miRNA induction and expression, and gene regulation by miRNA is hypothesized.

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As an important part of modern industry history of China, the Chinese Eastern Railway has been of irreplaceable historical significance and research value. Under the background of encouraging constructing low-carbon urban and town in China, the conservation tasks of protecting the Chinese Eastern Railway Culture Town would face new opportunities and challenges. This paper tries to explore how to apply the low-carbon planning approaches into the conservation planning of Hengdaohezi Town by analyzing and interpretating the status quo of the town.

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This paper, based on the theory and methods of urban design, analyzes the effects of stimulating and driving the space vitality from economic, social and cultural aspects. It is trying to find out main problematic issues of the protection planning of Chinese Eastern Railway Culture Town and to explore the methods of shaping vitality of historic culture town. In addition, it also produces an empirical research taking the town of Hengdaohezi as the case study.